Jillian Freese, Ph.D.
Red Algal Parasitism
Choreocolax polysiphoniae & Vertebrata lanosa
My Ph.D. research mainly focused on the development of the red algal parasite Choreocolax polysiphoniae and the response of its host, Vertebrata lanosa, to infection. I used morphological techniques (plastic and paraffin sectioning, histology, and in situ hybridization) to understand the morphological process of parasite development and used molecular techniques (modified single cell RNA extractions and RNA-Seq) to identify the genes that are differentially expressed throughout the infection. Combining these techniques gave a more comprehensive view of parasite development and host response.
The problem with Asterocolax
My Ph.D. research also involved understanding and clarifying the relationships between parasites in the genus Asterocolax and their hosts. The initial morphological description of Asterocolax in the 1950's led to the creation of an independent genus devoted to these parasitic species. But molecular data have repeatedly demonstrated that Asterocolax species, and likely many other red algal parasites, resolve within the genera of free-living red algae, often within the same genus as their host. The polyphyletic nature of Asterocolax supported its revision to re-establish monophyly. I carried out a taxonomic revision of the red algal parasitic genus Asterocolax, described a new species, and proposed nomenclatural changes for other Asterocolax species. We predict that most parasite-specific genera will be superfluous and in cases where multiple species are described, paraphyletic.